Jennifer Lopez has been caught up in what looks like the most ridiculous law suit ever — a man named Rodrigo Ruiz just sued the singer, claiming she duped him into sending her naked photos in the mail … but it appears a rando 53-year-old woman is secretly behind everything.

According to TMZ,

Ruiz filed the $10,000 suit against Lopez in L.A., claiming she sent him a letter in 2008 after he submitted a demo tape to someone he believed was in Lopez’ camp. Ruiz claims Lopez demanded he reply with naked photos … as well as more demo CDs.

He claims the letters led him to believe he had a chance at a music career — and even a romantic relationship with Lopez, but she never followed through and he eventually gave up hope. Ruiz says he was so depressed he sought out professional help.

Ruiz sent us a few of the 3-line letters he received from “Lopez” and they’re obviously bogus … the first reads, “I just wanted to let you know that I do remember you and that I am interested in you. I have plans on leaving my husband. But I can’t say much right now so that’s it for now. Send me pictures of you both with clothes and without clothes.”

Here’s the second — “This is Jennifer Lopez writing to you again and just to let you know that I got your packages, music, and demos. And just to let you know you need to send me pictures of you with and without clothes.”

The third is the best — “This is Jennifer Lopez and as you can tell its been a while since I last wrote and as you can see I have a new boyfriend which means your in for the long haul and you have to put up with the fact that I am f**king him and sucking his d**k.”

In addition to the lawsuit, Ruiz filed a police report claiming sexual harassment.

Ruiz still believes Lopez sent these letters to him, but records show the P.O. box he replied to is owned by a 53-year-old L.A. woman.

We called her to ask about the lawsuit and everything else, and she nervously concocted a lame explanation about operating a Jennifer Lopez fan mail exchange … and hung up on us.

A rep for J.Lo tells TMZ, “this is a small claims matter that appears to be a desperate attempt for notoriety. Ms Lopez has never seen or met the plaintiff, nor has she ever communicated with him. We believe this matter should be summarily dismissed.”